Growing a Plum Tree

Plum Tree

Plums
are popular for cooking, jam making and bottling or
canning, but the sweeter varieties are among our most
delicious dessert fruits. Damsons ripen a little later
than most plums. The fruits are small, oval and richly
flavored, but not really sweet enough for the general
taste for eating raw. They are, however, excellent for
cooking, preserves and bottling. Bullaces are small
round fruits, which ripen even later and are useful
on that account to lengthen the season. Bullaces can
be eaten raw but are excellent for cooking. Gages are
simply a class of plum with a characteristic, and particularly
delicious, flavor. Gages, bullaces and damsons are all
grown in the same way as plums.

Plums
will grow in most parts of the country but as they flower
early they are very vulnerable to spring frosts. The
choicer kinds deserve the protection of a wall where
protection from frost (and birds) can more easily be
given. They do best in districts where the annual rainfall
is between 50 and 90cm (20 and 35in). Damsons will succeed
in areas having higher rainfall, and less sunshine,
than plums will tolerate.

Plums
need a well-drained soil and one containing plenty of
humus to hold moisture during the growing season. A
very acid soil should be limed, but an alkaline soil
should not be planted with plums. Plums (and other stone
fruits) do need calcium but they will not prosper in
an alkaline soil. Plum trees planted in thin soils overlaying
chalk often suffer seriously from lime-induced iron
deficiency.

No
really satisfactory dwarfing rootstock has yet been
found for plums. The two least vigorous are common plum
and St Julien ‘A’; the former, however, is only compatible
with certain varieties. Trees grown on these rootstocks
are sometimes described as ‘semi-dwarf’ but, even so,
a standard or half-standard would be too large for the
average garden, and even a bush-type tree requires a
spacing of 4-5m (12-15ft) (on Brompton or Myrobalan
‘B’ rootstock, 6-7m [18-20ft]).

Because
plums do not produce fruiting spurs as apples and pears
do, they are not so amenable to training, and are seldom
satisfactory as cordons or espaliers. They may, however,
be grown as fans, for wall-training or with the support
of posts and horizontal wires, but root-pruning will
probably be necessary every five years or so to restrain
growth and maintain fruiting. A fan tree on St Julien
‘A’ rootstock should be allotted at least 5m (15ft)
of wall space.

Plums
may also be grown as semidwarf pyramids on St Julien
‘A’ rootstock and this is a form, which is best for
the small garden. Such a tree requires a spacing of
3.3m (10ft) and, as it will never be allowed to grow
much over 3m (9ft) in height, it is possible to arrange
some kind of cage or netting over the top of the tree
to keep off birds, which will otherwise damage the fruit.
An additional advantage is that the branches of a pyramid
seldom break and there is thus less likelihood of infection
by disease.

For
training as a pyramid a maiden should be planted in
the usual way and the following March it should be headed
back to 1.6m (5ft). Any laterals above 45cm (18in) from
soil level should be shortened by half and any arising
lower down the stem should be cut off entirely. Towards
the end of July or early in August, when new growth
has finished, cut back branch leaders to 20cm (8in),
making the cut to a bud pointing downwards or outwards.
Cut laterals back to 16cm (6in). Repeat this procedure
annually. Leave the central leader untouched in summer
but in April of the second year cut it back to one-third
of its length. Repeat this annually, cutting the new
growth back by two-thirds until a height of 3m (9ft)
is attained. After that shorten the new growth on the
central leader to 2.5cm (1in) or less each May.

Plant
plums in the usual way between November and March, the
sooner the better, always provided the soil is friable.
Stake securely and put down mulch to preserve soil moisture.

An
established plum needs plenty of nitrogen but, until
good crops are being carried, on most soils it will
be sufficient to give a light mulch of rotted farmyard
manure or garden compost in spring, and prick this lightly
into the surface the subsequent autumn. When good crops
are being borne, the yearly mulch may be supplemented
with 28g (1oz) per dressing of Nitro-chalk and 14g (0.5oz)
per sq. m sq. yd) of sulphate of potash, given in February.
Every third year, add 28g (1oz) per sq. m sq. ft) of
superphosphate. Where no manure or garden compost is
available, peat may be used as mulch and the dose of
Nitro-chalk doubled.

The
wood of plum trees naturally tends to be brittle and
branches often break in late summer gales when the crop
is heavy. Thinning of the fruit will help to prevent
this form of breakage, and it is also advisable to arrange
some kind of support for extra-heavily laden branches
on bush-type trees. Wooden props may be fixed beneath
branches (well padding the point of support) or a tall,
strong central pole can be erected and branches supported
from this by ropes, maypole fashion.

Dessert
plums should be left on the tree until quite ripe and
then picked by taking hold of the stalk so that the
place. They will keep for a couple of weeks or so.